Wasted heat recovery

ABSTRACT

This invention relates to a means for using waste heat to preheat water going to a water heater to reduce the amount of energy needed to raise the temperature of the water to a desired level. The invention, further, is portable so that it can be easily moved to accommodate the location of the waste heat source and water heater.

BACKGROUND OF THE INVENTION

There are several devices on the market that draw waste heat from clothes dryers, furnace flues, and other sources to warm the surrounding air. These devices typically involve installing a diverter unit at some point downstream of the heat source and directing the waste heat into a living space, hence reducing the energy that would need to be supplied to heat the air to the same temperature. While these devices work well for heating air adjacent to the source of waste heat, they are not suitable to preheating water going to a water heater because they are fixed and the water heater may not be in close proximity to the source of waste heat. The current invention eliminates this problem by providing a portable heat exchanger that can be readily moved and connected between the source of waste heat and the water heater.

Several patents have been issued which use waste heat to heat or preheat water, however, these appear to be of the permanent or fixed installation type. These include U.S. Pat. No. 7,360,580, 7,216,696, 6,749,014 and 6,564,755.

DETAILED DESCRIPTION OF DRAWINGS

The above and other objects, advantages and features of the present invention will be more fully understood when considered in conjunction with the attached drawings of which:

FIG. 1 is a dimetric view of the heat source and plenum assembly of the present invention with one side of the plenum assembly removed showing the elements of the heated air collection and transfer portion of the invention;

FIG. 2 is a dimetric view of a typical installation of the present invention with the outer shell of the heat transfer cabinet removed showing the elements of the heat transfer system according to the invention; and

FIG. 3 is a dimetric view of a typical installation of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a method of providing preheated water to a domestic or commercial water heater. The invention makes use of hot waste flue gases by using these waste flue gases to heat the air in a plenum chamber and redirecting the heated air through a heat transfer cabinet to preheat the water prior to its introduction into the water heater.

With initial reference to FIG. 1, the method can be accomplished by inserting a plenum assembly 1 into the flow of hot waste gases in the flue 7 from, but not limited to, a furnace 8, boiler, wood or pellet stove, clothes dryer, solar device or other source of heated air. As the hot gases move through the plenum flue 4, the air inside the plenum assembly 1 is heated. The amount of make-up air inside the plenum assembly 1 can be controlled by means of an adjustable shutter device 2. At a predetermined temperature, a switch 6 is activated and a high temperature blower 3 moves the heated air through duct work 5 to the heat transfer cabinet 9 in FIG. 2.

The heated air from the plenum assembly 1 in FIG. 1 enters the top of a heat transfer cabinet 9 in FIG. 3 from the duct work 5 and passes over and around a heat transfer assembly 16 shown in FIG. 2. Once the heat has been extracted from this air flow, the cooled air is vented from the heat transfer cabinet 9 thru an exhaust port 21 shown in FIG. 3. The heat transfer cabinet 9 is mounted on casters 10 to enable it to be easily moved and positioned relative to the chosen heat source. The heat transfer assembly 16 is made of tubing and other fittings arranged and assembled together in such a way as to provide a continuous path for water from a suitable water source 12 such as a municipal water supply, well, spring or other viable source. The tubing and fittings used in the heat transfer assembly 16 are made of copper, type L copper, aluminum or other suitable heat conductive material. The diameter of the tubing used and the effective length of its assembly can be varied to accommodate different heat sources and permit the water moving through the tubing to remain long enough to increase in temperature by at least 10° F. In one part configuration ½ inch tubing was used in an arrangement that provided approximately 196 feet of continuous pathway for the water and proved to be effective in increasing the water temperature by the desired amount. Included in the heat transfer assembly 16 are water hammer arrestors 15 to prevent pressure pounding in the system. As the heated air introduced from the plenum assembly 1 is forced over, around and through the tubing of the heat transfer assembly 16, heat is transferred through the tubing to the water moving inside. The pre-warmed water then exits the heat transfer cabinet 9 through approved tubing or hose 13 which is fitted with an approved quick detachable fitting or approved union 11 or other approved fittings and enters the hot water heater 14 where the heating is completed with a reduced consumption of energy. Hot water exits the water heater 14 through household plumbing 17 on demand.

The heat transfer cabinet 9 is made of a framework of wood or other suitable material. The outer covering of the heat transfer cabinet 9 is an insulated shell of exterior grade plywood, metal, molded plastic, fiberglass or other suitable material. The insulation is of sufficient thickness and composition such that heat loss is kept to a minimum. The dimensions of the heat transfer cabinet 9 can be customized so that the insulation is kept from contacting the heat transfer assembly 16 allowing the heated air to circulate freely over and around the tubing of the heat transfer assembly 16. The heat transfer assembly 16 is attached to cross members 19 of suitable material by means of standard tubing brackets 18 and is supported inside the heat transfer cabinet 9 on supports 20 of wood or other suitable material, thereby making it easily removable for inspection or repair. 

1) A portable heat exchanging apparatus for preheating water, said apparatus being made largely of tubing affixed to a framework such that it can be easily moved around to be connected between a source of waste heat and a water heater. 2) A portable apparatus as claimed in claim 1 in which the tubing is copper or some other heat conductive material and is of sufficient diameter and length to allow the water moving through the tubing to remain within the framework long enough to absorb heat provided by the waste heat source and increase the temperature of the water by at least 10° F. 3) A portable apparatus as claimed in claim 1 in which the blower that moves air from the waste heat plenum to the tubing flow is controlled by a thermostat and switch. 4) A portable apparatus as claimed in claim 1 in which the framework is made of wood or other inexpensive, non-heat absorbing material and is mounted on wheels, casters, or other such apparatus that makes it easy to move the heat exchanger to accommodate the location of the waste heat source and the water heater. The framework to also be well insulated to minimize heat escaping from the tubing inside the framework to ambient, while not interfering with the circulation of air around the tubing. 5) A portable apparatus as claimed in claim 1 in which one end of the framework is connected to a source of waste heat, including, but not limited to, exhaust from a clothes dryer, exhaust from a furnace, boiler or other source of home or industrial room heating. 6) A portable apparatus as claimed in claim 1 in which a device is inserted into the tubing to prevent water hammering. 